1/17/2024 0 Comments Alaska quake depth![]() ![]() The initial rupture on November 3, nucleating 22 km (14 mi) east of the foreshock, was on a thrust fault segment, the previously unknown Susitna Glacier thrust, to the south of the Denali fault. The calculated stress transfer from this foreshock indicates that it brought the Denali fault closer to failure at the location of the mainshock epicenter. Because of its location close to the November 3 event and the fact that it preceded it by only 11 days, this earthquake is regarded as a foreshock. Minor avalanches of snow and rockfalls were plenty in the area as a result. This rupture extends to 10 km (6.2 mi) west of the mainshock's epicenter. The event's aftershocks revealed a 45 km (28 mi) long fault rupture along the Denali fault, but aerial reconnaissance could not locate a surface rupture. On October 23, 2002, there was a magnitude 6.7 earthquake located on the Denali fault. The Denali-Totschunda fault system is one of the structures that accommodate the accretion of the Yakutat terrane. In Alaska, moving from east to west, the plate interactions change from a transform boundary between Pacific and North American plates to a collision zone with a microplate, the Yakutat terrane, which is in the process of being accreted to the North American plate, to a destructive boundary along the line of the Aleutian islands. ![]() The Denali-Totschunda fault is a major dextral (right lateral) strike-slip system, similar in scale to the San Andreas fault system. About 20 houseboats were damaged by a seiche on a lake in Washington State. Due to the remote location, there were no fatalities and only one injury.ĭue to the shallow depth, it was felt at least as far away as Seattle and it generated seiches on bodies of water as far away as Texas and New Orleans, Louisiana. The shock was the strongest ever recorded in the interior of Alaska. This 7.9 M w earthquake was the largest recorded in the United States in 37 years (after the 1965 Rat Islands earthquake). The 2002 Denali earthquake occurred at 22:12:41 UTC (1:12 PM Local Time) November 3 with an epicenter 66 km ESE of Denali National Park, Alaska, United States. Jibson concluded.Extent of surface rupture caused by faulting during the 2002 Denali earthquake But now we have seen enough earthquakes to know that it’s not just magnitude that affects landslides, it’s also focal mechanisms and tectonic settings and the frequency of earthquake waves,” Dr. “For the past 30 years we’ve made comparisons based on magnitude alone. The new evidence aids in understanding the complexity of predicting an earthquake's effect. On the contrary, severe damage to infrastructure was caused especially as cracks opened between artificial and natural slopes. Nevertheless, those findings do not imply that ground failures caused by the 2018 earthquake were minor. While the 1964 Alaska earthquake resulted from a massive rupture along the subducting boundary between the Pacific and North American plates, the 2018 earthquake occurred at a larger depth in a normal fault within a tectonic plate. “We feel pretty strongly that one of the reasons the Anchorage earthquake didn’t trigger so many landslides is because it was an intraslab event,” Dr. The researchers point out a major difference between the focal mechanisms of the massive tremblors that led to this fact. According to prediction modeling and the magnitude of the earthquake, a larger number of landslides was anticipated. Researchers concluded that the deep landslides triggered by the 1964 tremblor were not re-activated as the recent seismic shock had a lower duration and higher frequency.īy examining this phenomenon, scientists came to an interesting conclusion about the 2018 earthquake. ![]() The research team visited the affected region some days after the 2018 shock to record the ground failures including cracks, landslides and liquefaction phenomena. Geological Survey (USGS) and lead author of the study, some cracks appeared on the regions where landslides occurred back in 1964 but the shaking was not intense enough to cause any significant movement. It was the strongest tremblor the region has experienced since the 1964 incident, the most powerful ever recorded in the United States.Īccording to Dr. According to a new study, published in Seismological Research Letters, the deep landslides that were triggered by the massive M 9.2 Alaska earthquake in 1964 were not re-activated by the M 7.1 earthquake that hit Anchorage on November 30, 2018.Ībout a year ago, Alaska's largest city was struck by a massive earthquake that caused significant infrastructure damage but, fortunately, no casualties. ![]()
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